Since the first part of the twentieth century, it has been maintained that faster-than-light motion could produce time travel into the past with its accompanying causality-violating paradoxes. However, there are two different approaches to tachyon communication around a loop, one employs a "hand-off" between momentarily- adjacent observers in relative motion passing each other, while the other applies direct tachyon communication between moving observers who are not adjacent. Tachyon physics in the latter method clearly precludes causality violation, but it is more subtle in the former approach. An analysis of what would be observed in a physics laboratory, rather than what is inferred from a Minkowski diagram, attests that causality violation does not occur in the hand-off method, either. Thus it is demonstrated that tachyons do not violate causality.